#341 WIP Added sound mute toggle button to main menu.

android/assets/text/application/application_cs.properties

android/assets/text/application/application_de.properties

android/assets/text/application/application_sk.properties

...mmon/_global/application/mainmenu/icon_sounds_pressed.png

...on/_global/application/mainmenu/icon_sounds_unpressed.png

core/src/cz/nic/tablexia/TablexiaSettings.java

core/src/cz/nic/tablexia/game/GameDefinition.java

.../tablexia/loader/application/ApplicationAtlasManager.java

...c/tablexia/loader/application/ApplicationTextManager.java

core/src/cz/nic/tablexia/menu/IMenuItem.java

core/src/cz/nic/tablexia/menu/game/GameMenuDefinition.java

core/src/cz/nic/tablexia/menu/game/GameMenuItemGroup.java

core/src/cz/nic/tablexia/menu/main/MainMenu.java

core/src/cz/nic/tablexia/menu/main/MainMenuDefinition.java

core/src/cz/nic/tablexia/menu/main/MainMenuItemGroup.java

core/src/cz/nic/tablexia/menu/user/UserMenuItem.java

core/src/cz/nic/tablexia/screen/AbstractTablexiaScreen.java

core/src/cz/nic/tablexia/util/TablexiaSound.java